Quantum model of selective multiphoton processes: The role of external (field) and internal (anharmonic coupling) detunings

Quantum equations of motion describing the energy transfer dynamics via intramolecular anharmonic coupling are presented and solved numerically. Dynamical features of the average excitations of a homogeneous system (SF₆) and a heterogeneous system (H/W) are quantitatively discussed in terms of the intramolecular vibrational relaxation (IVR) rates. Possible mechanisms of surface-enhanced desorption via low-power laser radiation are proposed.This work was supported in part by the Office of Naval Research, the Air Force Office of Scientific Research (AFSC), United States Air Force, under Grant AFOSR-82-0046 and the National Science Foundation under Grant No. CHE-8022874Camille and Henry Dreyfus Teacher-Scholar (1975–82)     

GA-KBrO3-H2SO4体系化学振荡的研究

研究了GA(没食子酸)-KBrO_3-H_2SO_4体系的诱导期τ、振荡周期T_2与反应物起始浓度的依赖关系, 302 K时的经验式为τ=22.8 c~(-2.23)_(H_2SO_4) c~(-2.17)_(KBrO_3) c~(0.795)_(GA) (mol.dm~(-3))~(4.25)·sT_2=0.84 c~(-2.28)_(H_2SO-4)c~(-1.97)_(KBrO_3) exp{(0.000147(mol.dm~(-3))~2/c~2_(GA)}(mol.dm~(-3))~(4.25)·sτ及T_2都随~CGA的增加而增长, 这与B-Z反应中关于有机物的结论不同。用循环伏安法研究该体系的结果表明, GA在诱导期结束时就基本上都被氧化为中间物, GA并不象前人所认为的是维持振荡的物种, 实际参与振荡的是由GA生成的物质。本文还研究了Fe(Phen)_3~(2+)对GA-KBrO_3-H_2SO_4体系振荡的影响, 发现Br~-振荡行为随Fe(Phen)_3~(2+)的浓度而变。低~CFe(phen)_3~(2+)时,Br~-的振荡行为与GA-KBrO_3-H_2SO_4体系的基本相似, 其特征是每个振荡周期内, Br~-振荡脉冲发生前是逐渐积累的。随着~CFe(phen)_3~(2+)的增大, Br~-出现另一特征的振荡行为, 在每个振荡周期内, Br~-振荡脉冲发生前是逐渐减小。我们认为, GA-KBrO_3-H_2SO_4-Fe(Phen)_3~(2+)体系的振荡不能单一地用OKN机理加以解释, 它可能是两套振荡机理耦合的振荡。     

A microbial synthesis of R and S-9-hydroxy-(E)-2-decenoic acid(9-HDA), a queen honeybee pheromone

(R,E)-9-hydroxy-2-decenoic acid (9-HDA) its (S,E)- isomer have been prepared by using an organic-microbial approach.     

Pillared, 3D metal-organic frameworks with rectangular channels. Synthesis and characterization of coordination polymers based on tricadmium carboxylates

Hydro(solvo)thermal reactions between cadmium(II) perchlorate and 4-pyridinecarboxaldehyde in the presence of various guest molecules have resulted in a series of 3-D coordination polymers based on tricadmium carboxylates [Cd6(isonicotinate)10(H2O)2](ClO4)2(EtOH)4(H2O)4, 1, [Cd3(isonicotinate)5 (EtOH)](ClO4)(EtOH)(4-nitroaniline)0.5, 2, and [Cd6(isonicotinate)11](ClO4)(EtOH)2(H2O)2(4-cyanopyridine)0.5, 3. X-ray single crystal structure determinations show that they exhibit similar pillared, 3D framework structures based on tricadmium carboxylate building blocks. Rectangular channels are clearly present in these polymeric networks and are occupied by perchlorate anions and disordered guest molecules. Quantitative NMR and X-ray powder diffraction studies and thermogravimetric analyses (TGA) reveal that these coordination networks are capable of accommodating different guest molecules. More significantly, the guest molecules can be readily removed via evacuation to result in nanoporous polymeric coordination networks retaining the framework structures of the pristine solids. Crystal data for 1: monoclinic space group P2(1)/n, a = 19.041(1) A, b = 23.654(1) A, c = 21.568(1) A, beta = 95.440(1) degrees, and Z = 4. Crystal data for 2: triclinic space group P1, a = 12.050(1) A, b = 12.277(1) A, c = 19.103(1) A, alpha = 91.669(1) degrees, beta = 96.850(1) degrees, gamma = 117.945(1) degrees, and Z = 2. Crystal data for 3: monoclinic space group P2(1)/n, a = 19.038(1) A, b = 23.834(1) A, c = 21.756(1) A, beta = 97.580(1) degrees, and Z = 4.     

New Diterpene Alkaloids from Aconitum sungpanense var. leucanthum

Five new C₁₉ diterpene alkaloids, leucanthumsines A ( 1 ), B ( 2 ), C ( 3 ), D ( 4 ), and E ( 5 ), were isolated from the Chinese medicinal herb Aconitum sungpanense var. leucanthum, together with the known C₁₉ diterpene alkaloids pseudaconine, neoline, 1‐O‐methyldelphisine, crassicaudine, chasmanine, talatisamine, indaconitine, ezochansmanine, and leueantine D. The structures of these new alkaloids were elucidated by HR‐MS and advanced NMR methods, including ¹H‐ and ¹³C‐NMR (DEPT), ¹H,¹H‐COSY, HMQC, and HMBC experiments.     

First iodocyclization of β-allenic phosphonates: a novel synthesis of α-difluoromethylenephostones

Six-membered α-difluoromethylenephostones were prepared in moderate to good yields with high regioselectivities under mild conditions from the iodocyclization reaction of diethyl β-allenic α,α-difluorophosphonates using I₂ or ICl as the electrophile.     

The study and characterization of nucleosides by mass spectrometry—I: The mass spectra of pyrimidine 2,2′-anhydronucleosides and their derivatives

The mass spectra of 2,2′-anhydrouridine, 2,2′-anhydrothymidine and 2,2′-anhydro-4-thiouridine are reported. The acetyl, trifluoroacetyl, trityl, pivaloyl and trimethylsilyl ether derivatives were also studied. Deuterium labeling in acetyl and trimethylsilyl groups aided characterization of many ions in the spectra, as well as helping to clarify hydrogen migration processes. The anhydronucleosides and their derivatives are readily distinguished from natural nucleosides by the presence of an ion containing the base moiety plus the anhydro-ring plus one hydrogen atom from the rest of the molecule. As for natural nucleosides the [base + H]⁺ and [base + 2H]⁺ ions are usually prominent, but in contrast to natural nucleosides, ions characteristic of the sugar moiety do not retain the 2′-oxygen atom (i.e. the oxygen atom of the anhydro-ring). The mass spectra of deuterium labeled derivatives suggest a test for the presence of a 3′-O-acetyl function (the O-acetyl group is lost from the molecular ion much more readily from the 3′- than from the 5′-carbon atom). The trimethylsilyl derivatives showed evidence in their mass spectra for migration of trimethylsilyl groups in addition to hydrogen atoms.     

N(CH2CH2NH3)3][U3O2F13].2H2O: a novel organically templated mixed-valent uranium oxyfluoride with a hybrid network structure

The synthesis and characterization of a novel mixed-valent uranium oxyfluoride is described; the inorganic network consists of 2-D [U(2)F(10)](2)(-) sheets constructed from corner- and edge-sharing U(IV)F(9) tricapped trigonal prisms and 1-D [UO(2)F(3)](-) chains constructed from edge-sharing U(VI)O(2)F(5) pentagonal bipyramids with the organic cations and water molecules between the sheets. This is the first example with a hybrid network structure in the system of uranium fluoride or oxyfluoride. The variable-temperature magnetic susceptibility confirms the oxidation state of the uranium ions. Crystal data follow: C(6)H(25)N(4)O(4)F(13)U(3), monoclinic, space group P2(1) (No. 4); a = 8.6876(4) A, b = 7.3158(4) A, c = 16.3376(8) A, beta = 93.7285(9) degrees , V = 1036.2(2) A(3), and Z = 2.